By Andi Anderson
Soybean farmers constantly seek ways to improve crop performance and profitability. One growing question is whether foliar fertilizers—liquid nutrients sprayed on leaves—can boost yields.
Research from Michigan State University Extension (MSU Extension) and the Michigan Soybean Committee provides insight into this practice.
Soybeans absorb most of their nutrients through roots from the soil. However, plants can also absorb small amounts through leaf pores.
Micronutrients like manganese (Mn), boron, and zinc are more suitable for foliar feeding than macronutrients like phosphorus or potassium, which are required in much larger quantities.
Since 2011, MSU’s On-Farm Soybean Research Program has studied foliar fertilizers across 132 site-years. The results showed a significant yield increase only 9% of the time. Even in those cases, the gain didn’t always cover the cost of the product and application.
Foliar fertilizers can still play a role in correcting visible micronutrient deficiencies. For instance, manganese deficiency, common in Michigan’s high pH soils, shows as yellowing between green leaf veins. Applying 1–2 pounds of actual Mn at symptom appearance, followed by scouting and a second application if needed, is the recommended practice.
Foliar applications work best when combined with an existing sprayer pass to reduce added costs. It’s also helpful to leave non-treated strips in the field to measure the real benefit using a yield monitor or weigh wagon.
A national study involving 16 states during 2019–2020 tested six foliar products. The results showed no consistent yield gain, no grain quality improvement, and little or no profitability.
The conclusion? While foliar fertilizers may help correct nutrient deficiencies, they rarely lead to consistent or profitable yield boosts. MSU Extension continues to recommend using science-based strategies and encourages farmers to test products on a small scale before large investments.
Photo Credit: michigan-state-university-msu-extension
Categories: Michigan, Crops, Soybeans, Education